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(No Model.) G. W. GARDANIER.

DUPLEX AND MULTIPLEX TELBGRAPHY.

No. 280,028. Patented June 26, 1883.

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, NIER, a citizen of the United States, residing UNITED STATES PAT T OFFICE.

GEORGE \V. GARIDANIER, OF BROOKLYN, NEW YORK.

DUPLEX AND MULTIPLEX TELEGRA'PHY.

SPECIFICATION forming part of Letters Patent No. 280,028, dated June 26, 1883.

Application filed Dcccmherfifi, 1882. (No model.)

To all whom/ it may concern:

Be it known that I, GEORGE IV. GARDA- at Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Duplex or Multiple Telegraph Systems and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will. enable others skilled in the art to which it appertains to make and use the same.

The invention relates to an improvement in duplex or multiple telegraph systems; and its object is to prevent the static discharge of the main line from producing false signals upon the sounder or receiving-instrument at the home station during the process of transmitting signals therefrom.

My invention consists in the production, in the main line between the battery and earth at the home station, of a static discharge simultaneouswith and substantially equal to and of the same polarity as the static discharge of the main line, the effect being that the two discharges of like polarity will neutralize each other and permit the receiving-instrument at the home station to remain unaffected. The static charge of a telegraph-1ine,and the effect of its discharge upon the receiving-in. strument at thetransmitting-station, when not obviated, are well understood.

In the practice of my invention I place an inductive resistance coil or coils in the main line between the battery and earth, which permits the same to be charged in an opposite direction to that of the main-line charge, and viceversa, the current in the main line being always of opposite polarity to that with which the induction-coils are charged. Upon permitting the transmitting -key to assume its normal position, after the line has been charged in one direction and the induction-eoils in an opposite direction, the static discharge of the line and ofthe induction-coils will be of like polarity, and will be met by a static discharge of like polarity from the induction-coils toward the relay. The two currents of like polarity, meeting, will instantly neutralize each other, and the said discharge of the line will thus be prevented from producing false signals at the transmitting-station. By the arrangement of the induction-coil in the main line between the battery and earth I am enabled to simultaneously charge it with a current of opposite direction to that sent to the line; and as the extra or induced current of the said coilis always in the same direction with that with which it is charged, it will appear plain that the static discharge of the line and of the coil will be of like polarity and will neutralize each other without affecting the relay. The extra or induced current of the inductive resistance coil or coils renders ml the discharge of the line.

The invention will be readily understood by reference to the accompanying diagram, which illustrates it embodied in the apparatus at one of the terminal stations of a single-current system of duplex telegraphy; but it must be distinctly understood that the invention is applicable, with equally satisfactory results, to either single or double current systems of multi plc transmission.

Referring to the accompanying drawings A denotes the transmitter, which may be ac- 7 5 tuated by the finger direct or by the usual form of key in connection with an electro-magnet and local battery. The working end of the transmittcr-lever plays between the resting contact 13 and the swinging end of the pivoted 8o lever O, which, when in its normal position, rests upon the contact D. From the pivot end of the lever G the main line E extends to the distant terminal. A wire, l including the battery G, passes from the transmitter A 8 5- and merges at II, with the wire I leading to the contact I), and containing coils E, which offer a resistance equal to the internal resistance of the battery. From the point H a wire is continued to the point J, where it separates, 0

passing around the opposite end of the relay 5 K to the line E, being provided between the relay and line with the rheostat N, or equivalent device, whose resistance'is equal. to that of the main line. At one end of the relay K ,is the usual armature, I, which, in connection with the wires Q R, local battery S, and electro-magnet T, actuate the sounder V in the customary manner. I shall use one or more inductive resistance-coils L, according to the length and other varying conditions of the line.

When the transmitter A is depressed, a current in one direction is'sent from the battery G through the said transmitter and the lever O to the line E, and at the same time acurrent in an opposite direction passes from thcbattery to the point J, where it divides on the branches a I), that part of the said current which passes through the branch I) finding its way through the artificial line, main line, lever C, and transmitter A, back to the battery, while that portion on the branch a charges the induction-coil. L, an d. passes thence to the earth. Upon the opening of the transmitter A there will bea static discharge of the line, and also of the induction-coil L. The static discharge of the line will be in the opposite direction to the current with which it was charged, and the discharge of the indnctioircoil will be in the same direction in which it was charged, and the two discharges, being of the same polarity, will neutralize each other and prevent the discharge of the line from affecting the home relay.

The apparatus hereinbefore described does not constitute any part of the invention sought to be protected by this application, and is illustrated merelythat the invention claimed here in may be clearly understood. The relay K is of well-known construction, being provided with two separate coils having the same number of convolutions, and t'tl'lftllgfld so that when the current from the branches a- 5 pass through them they will have an equal and opposite magnetic effect upon their soft-iron cores, and

ment at the home station in the process of transmitting signals therefrom, which consists in the simultaneous production, in the main line between the battery and earth at the home station, of a static discharge substantially equal to and of the same polarity as the said static discharge of the line, the effect being that the two discharges of like polarity will neutralize each other and prevent the false signals, substantially as set forth.

2. In a duplex or multiple telegraph apparatus, an inductive resistance-coil placed in the main line between the battery and earth, and arranged to operate substantially in the manner and for the purpose set forth.

In testimony whereof I atfix my sign ature in presence of two witnesses.

GEORGE XV. GARDANIER.

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CHAS. 0. GILL, HERMAN Gosrow. 

